Jump to content
western

Intermittent clutch after replacement - O/D Rebuild (Combined Thread)

Recommended Posts

I am not sure they would-be pattern springs. D44 bought all the old new GKN stock for these when GKN stopped making them.

Share this post


Link to post
Share on other sites

Incorrect spring pressure wouldn't create an intermittent fault; you'd get a consistent amount of slipping all the time when disengaged.

Looking up how it operates: when engaged, the solenoid blocks a return from the pump allowing it to build pressure against the relief valve and the pistons to overcome the spring pressure. This means the return path is open when disengaged, with the pump simply circulating oil. Sensible as its not then using power. Western has obviously had it apart and scrupulously cleaned it, but is the return accessible enough that you can verify its not got a piece of casting flash or something stupid like that isn't partially blocking it and acting like the solenoid? Significant facts here: problem occurs when cold: Thick oil finds it harder to pass said blockage. Problem occurs after coming to a stop when warm: The pump - being driven by the gearbox output - doesn't produce any flow when the vehicle is stopped. This allows this theoretical piece of blockage to move from a position where it was previously passing oil to one where it doesn't, until such a point as flow drops off again or overcomes it. Either that or somehow the solenoid is getting actuated when it shouldn't?

Share this post


Link to post
Share on other sites

How about the spring seats?  They could be a little worn.  Something is preventing proper spring pressure clamping the brake pack.  Intermittent behaviour could be caused by thermal expansion of the mechanical parts or casing, or the thermal effect on the brake pack (fluid temperature, pack layer friction, expansion or contraction of plates).

Share this post


Link to post
Share on other sites

The springs sit directly on the cone clutch bearing carrier & act against the rear housing, see reb's strip down photos earlier, there are no separate spring seats. 

The solenoid is directly switched from the gearknob switch, this is the 12v feed to energise it, the earth goes from solenoid terminal to one of the OD attachment bolts. 

Share this post


Link to post
Share on other sites
23 hours ago, landroversforever said:

If you’re considering the possibility of cracks in the housing/bores, it’s probably worth having or doing some NDT like dye-pen testing. I assume it something you’d have access to at work Ralph? 

For those not in the know, with dye-pen (dye penetrant) you douse it in a dye which can wick into tiny imperfections. The object is then cleaned and sprayed with a developer which is like a chalky substance and you can then see the dye soak out of any imperfections. 

This is where my brain was going when I mentioned the cracked casing above, but confess I didn't know a process that could work with aluminium.

It has to be this, or as above, the solenoid leaking a little, pushing the cone just enough to push back the springs a little.

I have to wonder it it could be made to work with a lever, and no pump at all!

 

Share this post


Link to post
Share on other sites
1 hour ago, lo-fi said:

Incorrect spring pressure wouldn't create an intermittent fault; you'd get a consistent amount of slipping all the time when disengaged.

Looking up how it operates: when engaged, the solenoid blocks a return from the pump allowing it to build pressure against the relief valve and the pistons to overcome the spring pressure. This means the return path is open when disengaged, with the pump simply circulating oil. Sensible as its not then using power. Western has obviously had it apart and scrupulously cleaned it, but is the return accessible enough that you can verify its not got a piece of casting flash or something stupid like that isn't partially blocking it and acting like the solenoid? Significant facts here: problem occurs when cold: Thick oil finds it harder to pass said blockage. Problem occurs after coming to a stop when warm: The pump - being driven by the gearbox output - doesn't produce any flow when the vehicle is stopped. This allows this theoretical piece of blockage to move from a position where it was previously passing oil to one where it doesn't, until such a point as flow drops off again or overcomes it. Either that or somehow the solenoid is getting actuated when it shouldn't?

Interesting thoughts. I cant remember how accessible the oil passages are. Swapping the rear housing would solve all of this as the issue that Ralph had was clearly not caused by a problem there.

 

Ralph, if you get chance, could you post a pic of the relief valve setup please? This is the only thing I havent taken apart on mine so curious as to how it goes together!

Share this post


Link to post
Share on other sites
Just now, Bowie69 said:

I have to wonder it it could be made to work with a lever, and no pump at all!

 

I cant think how as you would have to put a central fork in to move the clutch, but both sides of the clutch have a function so the fork would get in the way. You would also have to seal the pivot as the whole thing is bathed in oil.

Share this post


Link to post
Share on other sites

Would it be worth rigging another temporary way of switching the solenoid? That would rule out any possible issues in the wiring to the switch on the gearstick.

Share this post


Link to post
Share on other sites
54 minutes ago, landroversforever said:

Would it be worth rigging another temporary way of switching the solenoid? That would rule out any possible issues in the wiring to the switch on the gearstick.

Simply detaching wires would prove this.. It's slipping when not engaged, so not powered. If no power applied and it still slips it proves it not the wiring.

 

The thinking of pressure building up and starting to move the cone clutch is one I considered too, hence replacing the solenoid originally.

Good resources:

https://www.buckeyetriumphs.org/gearbox

https://www.landypedia.de/index.php/Überholung_eines_GKN_Overdrives

Share this post


Link to post
Share on other sites

I was thinking it still gave you the option to engage it when testing. I’m thinking there might be a short in the wiring somewhere.  

Share this post


Link to post
Share on other sites
1 hour ago, landroversforever said:

Would it be worth rigging another temporary way of switching the solenoid? That would rule out any possible issues in the wiring to the switch on the gearstick.

Its had two different sets of wiring tried on it at least so I don't think it can be this.

Share this post


Link to post
Share on other sites

I'll remove the 12v feed fuse & see what happens tomorrow on the way to work, that way I know no loose wiring will be flapping about underneath, it'll give the same affect as disconnecting the 12v feed on solenoid. the wiring in my 110 is fine it worked fine with the original OD fitted.


 

5 hours ago, reb78 said:

Interesting thoughts. I cant remember how accessible the oil passages are. Swapping the rear housing would solve all of this as the issue that Ralph had was clearly not caused by a problem there.

 

Ralph, if you get chance, could you post a pic of the relief valve setup please? This is the only thing I haven't taken apart on mine so curious as to how it goes together!

borrowed from this website https://www.landypedia.de/index.php/Überholung_eines_GKN_Overdrives

it has 2 concentric coil springs 

this valve in both my  OD rear cases is spotless clean & no apparent damage

 

From left to right: Valve body, control piston, shims, springs, spring cup, front hole cover. Above is the cylinder of the dashpotDashpot.jpg

 

 

 

 

Fuse removed & solenoid does NOT operate when ign is on & gear knob switch is switched to on. 

Share this post


Link to post
Share on other sites

At work now, even with the solenoid empower disabled OD slipped 5 times on the way to work, worst occurrence as pulling away from a give way line on a roundabout, took a reduction of revs to almost idle to get OD to grip & give some drive. So solly can be discounted as the cause. 

Share this post


Link to post
Share on other sites

Did you have the (main) clutch engaged when letting the revs drop to idle at the give way? If so, it feeds into my theory about an intermittent blockage needing oil flow to drop to reset. If that is the case, it's either a foreign object (casting flash or core remnant, perhaps) or the solenoid is somehow randomly  dropping in against its return spring when oil flow drops to zero as you come to a stop, but I think the latter unlikely. 

Share this post


Link to post
Share on other sites

Only a little just enough to keep the main gearbox engaged, but I don't believe that is the problem as the OD is meant to be engaged & disengaged under power without using the vehicles clutch. 

I will check the original rear case before fitting it with new piston seals & new filter to see if the oil ways are clear. 

Edited by western

Share this post


Link to post
Share on other sites
3 hours ago, western said:

Only a little just enough to keep the main gearbox engaged, but I don't believe that is the problem as the OD is meant to be engaged & disengaged under power without using the vehicles clutch. 

That is right.  That’s the benefit of epicyclic gears with clutch pack selectors - everything is already meshed, so you can have instant changes without removing torque.  It’s how automatic transmissions work, and this is essentially a two speed auto.

  • Like 1

Share this post


Link to post
Share on other sites

It's a clever design. I was more wondering about what the oil pump may or may not have been doing while you were stopping/failing to start/finally getting going. Interested to see how it behaves with the other rear casing. Fingers crossed! 

Share this post


Link to post
Share on other sites

in the parts pack from overdrive repairs is hopefully seals for the pump & relief valve. so that would be good to rule duff seals out.

Share this post


Link to post
Share on other sites

the parts pack from overdrive repairs arrived today, so I now have a nice new clean filter for the rear section & seals for the pistons, solenoid & other items

 

IMG_20191016_191958.jpg

the 3 smallest O ring seals are for the solenoid internal rod & next 2 bigger seal are for the solenoid outer rod.

IMG_20191016_192014.jpg

Piston seals x 2 below pen nib

IMG_20191016_192022.jpg

Solenoid seals x 2 below pen nib

IMG_20191016_192044.jpg

nice shiney new clean filter & gasket 

IMG_20191016_192053.jpg

  • Like 1

Share this post


Link to post
Share on other sites

not much progress so far, but I have made sure all the fluid galleries in my original rear case are clear of dirt & any other items that could cause a restriction, so I'll be building it up tomorrow ready to swap over & hopefully all this work/expense will make this OD work properly.

I will take some photo's as it progresses to 'ready to fit' state

 

I have found that the seal kit shown above contains the seals for the relief valve, fluid pump & solenoid seals.

  • Like 1

Share this post


Link to post
Share on other sites

I hope you finally get a good result for all the effort and expense you’ve gone to.

Share this post


Link to post
Share on other sites

This afternoon & evening has mainly be taken up by fitting the new seals to the relief valve, fluid pump & replaced the seals on my newer spare solenoid & the new circular filter in to my original overdrives rear casing,  the flat filter in sump & the magnetic strip cleaned, I also bought a new brake cone as well I know the existing cone was new but I didn't want to be taking the OD off again to replace the cone, 

some photo's below 

so & after fitting this lot to the 110 & doing a 18 mile test drive on local town roads, a run down to Hayle & back home along the A30, all seems to be OK,  

I'll check the fluid level in the morning, hopefully the OD should work fine now. :D

IMG_20191019_125012.jpg

Relief valve with new seals fitted & old seals above their respective locations

 

IMG_20191019_125315.jpg

relief valve sleeve in rear case of overdrive, the cut out & fluid drilling must be inline 

 

IMG_20191019_125324.jpg

relief valve pin located in the rear case.

 

 

IMG_20191019_125356.jpg

the 2 springs located on the relief valve pin.

IMG_20191019_125414.jpg

relief valve outer sleeve located over the 2 springs & pin. then the end cap is screwed down tight.

 

IMG_20191019_125631.jpg

circular filter location.

 

IMG_20191019_125714.jpg

new circular main fliter,gasket & end cap with new seal fitted.

 

IMG_20191019_125753.jpg

new filter & gasket in place, then end cap is screwed down tight.

 

 

 

  • Like 1

Share this post


Link to post
Share on other sites

IMG_20191019_130454.jpg

OD fluid pump parts, old seals above their respective locations & new seals fitted.

 

IMG_20191019_130628.jpg

housing fitted ready for the concentric offset drive from main shaft.

 

IMG_20191019_130647.jpg

bottom part of pump assembly in place, the fluid way must match the rear case drilling

 

 

IMG_20191019_130851.jpg

 

pump relief valve seat in place, a ball bearing sits in the centre, it's spring in the end cap.

IMG_20191019_130922.jpg

ball bearing valve in place 

 

IMG_20191019_131004.jpg

fluid pump end cap & spring, this was fitted & screwed down tight.

 

 

IMG_20191019_131051.jpg

 

all 3 caps tight in place, ready for the swap over to become the operational overdrive.

  • Like 1

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.


×
×
  • Create New...

Important Information

We use cookies to ensure you get the best experience. By using our website you agree to our Cookie Policy